JPA或Hibernate生成一个（非主键）列值，而不是从1开始 [英] JPA or Hibernate to generate a (non primary key) column value, not starting from 1

问题描述

我想要一个可以生成列值的JPA / Hibernate（最好是JPA）注释，它不是主键，它不能从1开始。

从我看到的JPA不能用@GeneratedValue和@SequenceGenerator和@TableGenerator来做到这一点。或与其他任何东西。

我已经看到一个解决方案与一个额外的表，我发现它不是优雅的。

我可以使用Hibernate注释，因为我已经有了hibernate注释。 / p>

我想使用@Generated，但我无法使其工作，并且人们声称

pre code $ @Generated（GenerationTime.INSERT）
private private invoiceNumber; // invoice数字

更新：额外的要求，如果事务回滚，我们不能有差距在编号中。
任何人？

解决方案

以下是我的工作原理 - 我们在服务中编写了所有代码。
这是实体：

pre $ @Entity
@Inheritance（strategy = InheritanceType.SINGLE_TABLE）
public class Registrant extends AbstractEntity {
// ....
private long invoiceNumber; // invoice number

@Entity
public static class InvoiceNumberGenerator {
@Id
@GeneratedValue
private int id;
私人长柜台;

public int getId（）{
return id;
}

public void setId（int id）{
this.id = id;
}

public long getCounter（）{
return counter;
}

public void setCounter（long counter）{
this.counter = counter;
}
}
}


然后我们有一项服务（实际上没有魔法，全部手动完成）：

  public synchronized注册者保存（注册人注册人）{
 long counter = getInvoiceNumber（）; 
 registrant.setInvoiceNumber（counter）; 
 
返回registrantRepository.save（注册人）; 
 
 $ b private long getInvoiceNumber（）{
 // mist：从另一张表中获取发票号码
 long count = registrantInvoiceNumberGeneratorRepository.count（）; 
 if（count> 1）{
 throw new RuntimeException（：InvoiceNumberGenerator table has more than one row。Fix that）; 
} 
 
 Registrant.InvoiceNumberGenerator生成器; 
 if（count == 0）{
 generator = new Registrant.InvoiceNumberGenerator（）; 
 generator.setCounter（1000001）; 
 generator = registrantInvoiceNumberGeneratorRepository.save（generator）; 
} else {
 generator = registrantInvoiceNumberGeneratorRepository.findFirstByOrderByIdAsc（）; 
} 
 
 
 long counter = generator.getCounter（）; 
 generator.setCounter（counter + 1）; 
 registrantInvoiceNumberGeneratorRepository.save（generator）; 
 return counter; 
 
 $ / code> 

请注意 synchronized 方法 - 所以没有人可以得到相同的数字。

我不相信没有什么能够做到的自动化。

I want a JPA/Hibernate (preferably JPA) annotation that can generate the value of a column, that is not a primary key and it doesn't start from 1.

From what I have seen JPA cannot do that with @GeneratedValue and @SequenceGenerator and @TableGenerator. Or with anything else.

I have seen a solution with an extra table, which I find is not elegant.

I can live with a Hibernate annotation, because I already have hibernate annotations.

I want to use @Generated but I cannot make it work and people claim that it is possible.

@Generated(GenerationTime.INSERT)
private long invoiceNumber;//invoice number

Update: an extra requirement, if the transaction is rolled back, we can't have a gap in the numbering. Anyone?

解决方案

Here's what worked for me - we coded all of it in the service. Here's the entity:

@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
public class Registrant extends AbstractEntity {
    //....
    private long invoiceNumber;//invoice number

    @Entity
    public static class InvoiceNumberGenerator {
        @Id
        @GeneratedValue
        private int id;
        private long counter;

        public int getId() {
            return id;
        }

        public void setId(int id) {
            this.id = id;
        }

        public long getCounter() {
            return counter;
        }

        public void setCounter(long counter) {
            this.counter = counter;
        }
    }
}

And then we have a service that does the magic (actually there's no magic, all is done manually):

public synchronized Registrant save(Registrant registrant) {
    long counter = getInvoiceNumber();
    registrant.setInvoiceNumber(counter);

    return registrantRepository.save(registrant);
}

private long getInvoiceNumber() {
    //mist: get the invoice number from the other table
    long count = registrantInvoiceNumberGeneratorRepository.count();
    if(count > 1) {
        throw new RuntimeException(": InvoiceNumberGenerator table has more than one row. Fix that");
    }

    Registrant.InvoiceNumberGenerator generator;
    if(count == 0) {
        generator = new Registrant.InvoiceNumberGenerator();
        generator.setCounter(1000001);
        generator = registrantInvoiceNumberGeneratorRepository.save(generator);
    } else {
        generator = registrantInvoiceNumberGeneratorRepository.findFirstByOrderByIdAsc();
    }


    long counter = generator.getCounter();
    generator.setCounter(counter+1);
    registrantInvoiceNumberGeneratorRepository.save(generator);
    return counter;
}

Note the synchronized method - so that nobody can get the same number.

I can't believe there's nothing automatic that can do that.

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